Most tattoo artists prefer not to share the tricks and tales of their trade, but not Jeff Johnson. In his newly released memoir, Tattoo Machine, the Portland-based inkman shares some of the weirdest, wackiest and most disgusting details of his profession, from cleaning up after chudders (look it up) to the time he tattooed a serial killer (he thinks). TIME spoke with Johnson about writing his first book, the grim reality of his work and the clash of tattoo generations.
(Read "Hate That Tattoo? Making Them Easier to Remove.")

In the book's introduction, you mention how nobody speaks for the tattoo industry, and that most artists like it that way. Were you worried about a backlash?
I was a little bit worried. In tattooing there's always been a great deal of secrecy: "Don't talk about this kind of stuff to outsiders." A friend of mine, Mary Jane, a tattoo artist, had a newsletter at one point, and people started threatening to kill her. There's a lot of weird stuff like that. But the reaction so far has been really positive. No death threats yet.
(See pictures of Olympic athletes' tattoos.)

Why is there such secrecy?
I think, historically, most tattoo artists didn't want people to have any kind of information they wanted, that it would just increase competition. But I think the secrecy is fading now because that's really not the case anymore. You really have to learn how to draw and get a good apprenticeship before you can get into the field.

But the rivalries between shops remain.
Back on the Long Beach Pike [in California], artists used to drive cars into each other's shops. They'd hire Marines to go in there and beat up everybody. These days, that doesn't really happen anymore. If you have a rivalry with another shop it's usually a good-spirited competition. Occasionally bad things do happen; there was one shop in Portland that was really, really bad. It was on the outskirts of town and another shop run by real professionals started up out there, and the warfare between these two places just escalated. One shop would hide eggs in the walls of the other place and the retaliation for this would be something so much more wickedly gruesome that you couldn't even imagine. Of course the bad shop eventually lost because their creative problem-solving skills were not up to par.

You included a glossary of slang terms in your book; would words like chud and night hog be recognized in tattoo shops throughout the country?
Every shop has their own slang. A lot of the slang I mention in Tattoo Machine would be recognized by anybody that works in Portland, probably a lot of people in Seattle as well, and California. But a friend of mine was just out working on the East Coast and he called and told me about all the colorful slang that they had, and it was all really different  some of it was really rude too. If I went to a shop in the Ozarks and it was really busy and everyone was working, there would probably be long stretches of time where I had absolutely no idea what they were talking about.

Tell me about the tattoo parlor you work at, the Sea Tramp in Portland.
It's a fascinating place. It was started by a guy named Bert Grimm, who allegedly tattooed Bonnie and Clyde and Buffalo Bill when he lived in St. Louis. He moved to Portland and retired, but decided that he couldn't stand to be retired so he opened up this shop that I currently own part of. There's so much ancient stuff there. We have an incredibly old piano in our storeroom and nobody knows how it got there. We actually found a Tommy gun in there one time. We had a couple of police officers come in for tattoos and when they found out about it, one of them said, "Oh, you should bring it out and let me look at it." It turned out the gun was loaded all this time.

You write that the flash art on the walls of your shop demonstrates four very distinct generations.
At the Sea Tramp, we have a lot of art drawn in very different eras, like Bert Grimm's stuff. Some of it is 50, 60 years old. The tattoo artists of his era  and this is not a very popular opinion  they couldn't draw very well. The lettering is very crude, the designs are flat, one-dimensional, not very original, very cartoony and extremely primitive. Then you move up to the tattoo artists that began in the '70s, and a lot of these guys could really draw. There's more color. In Bert Grimm's time they had three colors  black, green and red  and they weren't too sure about the red, and they weren't too sure about the green. Then the next group up is my group, the late '80s and early '90s. No Tasmanian devils, no half-naked pirate chicks or Harley Davidsoninspired stuff. Everything we were doing was like fantasy art, and all of this art kind of reflects what the customer is looking for. That's the whole reason you draw flash, so you have something prepared. We have two guys now in their early 20s, and they have actually gone back to the beginning, they're drawing slightly more complicated versions of that really old-school flash  horseshoes, cabbage roses, pirate heads.

You note that only two other professions brush up against drugs as often as tattoo artists  the police and the lost-and-found guys at the airport. Why is that?
People always assume that because you're a tattoo artist that you do drugs. There's still a lot of that countercultural stigma associated with the whole field. People just kind of assume you're going to be a dirtbag because of your job, but in tattooing that's just not true anymore. There are tattoo artists out there that have never even drank a single beer in their life, and go to church.

Do you have a favorite story you like to tell when someone asks you about your job?
I guess it depends entirely on what mood I'm in. A lot of people ask me, "What is your main regret?" I have to say that every tattoo artist will have the same answer to this question, and it's that eventually, one day, everything you made will be gone. There will be a time when my life's work will vanish from this world. And that's the real, only downside to tattooing  that it's on people, and people just don't last forever. But if that's the only downside, then it's really not that bad, you know?